Significant Accounting Policies (Schedule of Supplemental Cash Flow Information) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Schedule Of Supplemental Cash Flow Information [Line Items]
Financing leases	$ 26	$ 32
Operating leases	135	85
Virginia Electric and Power Company
Schedule Of Supplemental Cash Flow Information [Line Items]
Financing leases	22	31
Operating leases	$ 120	$ 68